''Whether you agree with him or not, P.J. writes a helluva piece.'' Richard Nixon P.J. O''Rourke has had a prolific career as one of America''s most celebrated humourists. But that career almost didn''t happen. As he tells it, ''I began to write for pay in the spring of 1970To tell the truth I didn''t even mean to be a writer, I meant to be a race car driver, but I didn''t have a race car.'' Fortunately for us, he had to settle for writing. From his early pieces for the National Lampoon (''How to Drive fast on Drugs While Getting Your Wing-Wang Squeezed and Not Spill Your Drink''), through his classic reporting as Rolling Stone''s International Affairs editor in the 80s and 90s (''Among the Euroweenies''), and his brilliant, inimitable political journalism and analysis (Parliament of Whores, Give War a Chance, Eat the Rich), P.Jhas been entertaining and provoking readers with high octane prose, a gonzo Republican attitude and a rare ability to make you laugh out loud while silently rea